How old are they? More than a couple years old, I'd trash 'em, especially if they've froze over the winter. Many car waxes don't do well after freezing, even if they look OK.
If your paint is in really good shape and just needs some sprucing up, check out Meguiar's NXT, Mothers FX Synwax or Mothers carnauba cleaner wax. The first two offer more durability but don't polish/clean paint all that well. The Mothers carnauba is your more traditional car wax with a mild polishing agent that helps with somewhat neglected paint.
If the paint's looking a bit rough, check out NuFinish or Turtle Wax F21 (Finish 2001). I hate recommending these waxes because I think their cleaning agents are too aggressive (both chemical and abrasive), but for store bought products under $10, they work fine.
If you want a one-step cleaner wax and are not adverse to ordering online, check out Klasse All In One. An excellent light paint cleaner combined with an acrylic polymer means a nice polish with some pretty durable protection. For more durability and shine, top it with Klasse Sealant Glaze and you'll get close to 4-6 months of protection. You can find Klasse kits online for about $45.00.